april2023 - 14

Service hitlist
for older trucks
Here's a quick hitlist of key service items
a fleet will want to start looking at once a
truck-tractor cruises past the 500,000-mile
threshold.
* Inspect rubber seals on aftertreatment system
composite connectors for water and
corrosion intrusion
* Consider proactively replacing the DOC if
the frequency of active regens increases
dramatically
* Replace transmission fluid and filter per
OEM recommendation
* Perform teardown inspection of rear axle
wheel ends, paying close attention to
bearing wear pattern and replacing wheel
seals
* Replace oil on steer and rear axles
* Change power steering fluid and filter,
paying close attention for signs of metal in
the filter pleats which would necessitate
further inspection
* Flush, drain, and refill extended-life coolant
* Inspect wiring harnesses and harness connectors
for chafing
* Inspect drum brake cams and bushings for
wear or damage. Look for signs of oil, transmission
fluid, and coolant leaks
* Consider proactively replacing O-rings and
seals in lubrication syste
* Consider starting an oil analysis program
* Inspect braking system hoses for cracks
and damage, especially where plastic
connectors are being used; simply replace
when in doubt
* Inspect the entire air dryer and consider
proactively replacing
* Consider replacing leaf springs, air bags,
and rear suspension; first inspect mounting
points and suspension spring components
for cracks or missing spring stacks,
inspect air bags for cracking rubber and
chafing, and look for leaking airline connections
and level valve binding
* Start planning for an engine rebuild around
750,000 miles or sooner if the vehicle has
been operated in a harsh environment
* Inspect all clutch parts, paying attention to
clutch free play and grab height to gauge
lining wear
Editor's Note: Always refer
to your vehicle's owner's
manual for specific maintenance
interval recommendations
based on age,
hours, mileage, duty
cycle, average idle time,
fuel economy, etc.
» When developing a maintenance
strategy for vehicles that are well past
their normal trade cycle, the first step
is to assess how well maintenance has
been performed up until that point.
Kenworth Northeast
getting right. These types of simple actions could
help extend the life of things like fuel injectors and
fuel pumps. But if these steps have been ignored
for the first four years of service, the damage may
have already been done. "
So, then what?
Drivers and technicians should be on the lookout
for even the smallest of oil leaks.
" Even something like a front cover that's starting
to get wet must be reported, " said Jeff Celantano,
technical data manager at Diesel Laptops. " It
might not create a problem right then and there,
but it will likely turn into a problem when you
least expect it. The same can be said for hydraulic
oils and engine coolant. "
Discoloration in the oil is another indication
of real trouble.
" If they aren't doing it already, we always
encourage our customers to start doing oil
analysis once a vehicle is over 500,000 miles, "
Kenworth Northeast's Ellis said. " Even just doing
it every other oil change or even once a year can
be beneficial. "
Tech training is also key. Oil samples must be
captured midstream and properly labeled. The fleet
14 Fleet Maintenance | April 2023
also needs to partner with a good lab so analysis is
reliable and consistent. " Oil sampling can be a great
tool, but only if it is done correctly, " Nynas said.
In addition to engine oil, it can be beneficial
to take samples from the transmission and drive
axles. " This can give fleets a good look at the
health of the assembly, as well as what's going
on in places that are not visible, " said Anthony
Balkonis, VP of services and warranty at Navistar.
More thorough electrical inspections also
become essential as a vehicle ages, particularly
vehicles that were somewhat neglected during
their earlier years. Technicians should take a good
look at wiring harnesses and harness connectors
for things like chafing.
Paying special attention to the electrical system
is even more important if the vehicle has been
operated in a more punishing environment.
" If the unit was operated in Rust Belt areas, it is
common to begin seeing the effects of climate and
road conditions on the electrical system, primarily
grounds, " said Andrew Plant, manager of
powertrain service engineering at Daimler Truck
North America. " Maintaining a good electrical
system, including batteries, cables, and grounds
is critical to proper electronic engine controls. "
The half-million-mile hurdle
In addition to ramping up PMs, there's a good
chance fleets will also start running into a new
april2023

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